This invention relates to helical conveyors of the kind having a helical flite fixed to a rotary shaft within a casing. Such conveyors are used with success with a great variety of pulverous and semi-fluid products.
Considerable difficulty however has been experienced in dealing with products which tend to solidify and jam between the screw and housing. For example, combustible waste products are heated to a very high temperature e.g. 1650.degree. F. for removal of moisture and are fed through a conveyor into a furnace. These products are very fluid at that temperature and run freely through a downpipe into the entry end of the conveyor where they rapidly become cooled e.g. to 300.degree. F. at which temperature the products tend to solidify and pack together and stop the helical conveyor. Attempts have been made to overcome this problem by using a larger horsepower motor to drive the conveyor and for example from a nominal 3 horsepower successive tests finally reached 25 horsepower which is obviously impractical.